Napoli threw away a two-goal lead as Mauro Icardi's late penalty earned Milan a 2-2 draw against 10 men, while Roma suffered more frustration in a goalless stalement at Chievo that was overshadowed Federico Mattiello's horrific leg break.
Rafael Benitez's Napoli were hoping to cut the gap to second-placed Roma and an automatic UEFA Champions League spot in their Serie A contest at Stadio San Paolo.
Gonzalo Higuain spurned a series of first-half chances as Napoli were frustrated at the break, but the tension was eased in the 51st minute when Marek Hamsik headed home Henrique's cross.
Argentina international Higuain then scored with a splendid 20-yard effort to double the advantage, only for Rodrigo Palacio to start Inter's comeback in the 73rd minute.
And Napoli were left to rue missing their early opportunities when Henrique pulled Fredy Guarin to the ground - earning the full-back a second yellow card - and Icardi kept his cool with a chipped penalty to secure Roberto Mancini's men a point.
Earlier, Roma drew for the eighth time in their past nine league matches at lowly Chievo - but Mattiello's injury grabbed most of the attention in an otherwise unremarkable contest.
The Chievo man - on loan from Juve - bent the lower part of his leg into a right angle in a challenge with Roma's Radja Nainggolan, before he was taken from the pitch on a stretcher.
Torino's hopes of playing European football next season suffered a blow in a 3-2 defeat at Udinese.
Fabio Quagliarella put the away side ahead after the 15th minute, but goals from Antonio Di Natale and Molla Wague either side of a Cristian Molinaro penalty put Udinese in control.
Marco Benassi pulled a goal back with just over 20 minutes remaining, but it proved to be a mere consolation.
Atalanta moved four points clear of the drop zone after being held to a frustrating 0-0 draw at rock-bottom Parma, who finished the match with 10 men.
The hosts, who are in dire financial straits, reached an agreement with stewards in order that the contest could go ahead.
Struggling Cesena also played out a 0-0 draw at home to Palermo, while Empoli and Genoa finished 1-1.